ES6 default parameters cause two write references

[bakkot]

(@michaelficarra)

See for example this test:

escope/test/es6-destructuring-assignments.coffee

Lines 340 to 346 in f237eef

	expect(scope.references[1].identifier.name).to.equal 'c'
	expect(scope.references[1].isWrite()).to.be.true
	expect(scope.references[1].writeExpr.name).to.equal 'e'
	expect(scope.references[1].partial).to.be.true
	expect(scope.references[1].resolved).to.equal scope.variables[2]
	expect(scope.references[2].identifier.name).to.equal 'c'
	expect(scope.references[2].isWrite()).to.be.true

Note that there are two references with name c and isWrite() true: that is, two write references to c. This despite the fact that c will be written precisely once by the sample code. This is especially confusing if you're looking at const-correctness.

Is this intentional? If so, what's the reasoning behind it?

[michaelficarra]

Ping @mysticatea, author of 23bb40b which added the referenced tests.

[mysticatea]

escope has been making a writable reference for variable initializers, so I treated default parameters and default values of destructuring as same as that.
Currently, references for initializers, default parameters, and default values are have a property init as true.

(Thanks @michaelficarra)